Port of Rotterdam
The depth of Rotterdam port is guaranteed by continuous dredging operations. The dredged sediments are trans¬ported to a dump location 5 km from the coast and are dumped in 18 me-ters deep water ‘Loswal Noord’. After intensive use of this location, it turned out that an important part of the dumped sediment migrated back to the port.
To improve the effec¬tiveness of the depot, it has been shifted about 10 km seawards to ‘Loswal Noordwest’.. To de¬termine its effectiveness, The National Institute for Coastal and Marine Management (RIKZ/RWS), started a large monitoring pro¬ject, which investigated the silt movement and environmental effects. The MEDUSA system was used to monitor the transport of silt. Therefore three campaigns have been conducted: the first campaign (t0) started before the silt dump, the next two cam¬paigns were executed after 1 and 1.5 year during and after dumping.
Results
The figures depict the silt distribution in the first and last measure campaign. Both figures clearly reveal the former dump¬ing location ‘Loswal Noord’ (in the right bottom corner of the measured area). In the measurement of June 1996, the remaining sea bottom is nearly silt free. In the results of the later measurement the new dumping location ‘Loswal Noordwest’ is distinctly visible. Also, two silt plumes that originate from the dump location are discernible. These measurements exhibit that silt is partly transported to the north by the net tidal current. The second plume, however, shows that silt is moving into the direction of Rotterdam port as well.
With these results a mass balance of the dumping activities is determined and the spread of material can be com¬pared with model calculations.
The quantitative information on the sludge dispersal has been used to validate the results of model calculations and can help to refine models for an improved assessment of the effectiveness of a spoil depot.
More information:
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